Every drop of sewage water collected from the girls’ hostel of the Tamil Nadu Agricultural University – Engineering College and Research Institute at Kumulur near here is being treated and let off into an open well of the institute for irrigation for paddy, maize, and horticultural crops.

The availability of sprawling area on the campus has facilitated the purification process. The wastewater, which contains heavy metals, is purified in two phases. A channel has been dug for about 10 metres and the black wastewater is first passed through a thickly grown reed bed. Outside the bed, the colour of the raw sewage changes, indicating its partial purification. The semi-treated water then is let into the thickly cultivated kal vazhai (cana indica) plants. “It may be hard for you to believe that the sewage water becomes pure beyond the kal vazhai bed,” says K. Ramaswamy, Dean of the Institute.

He explained that the reed and kal vazhai acted as a natural agent for purification of the sewage water. The sewage water from the hostel contains a large number of organic impurities, which are first purified by the reed plants. The kal vazhai absorbs heavy metals such as aluminium, iron, and phosphorous and their compounds and grows on them...................Read more

Source: The Hindu